Fig. 1.

Early plaque-associated neuritic dystrophy pathology in PS1/APP hippocampus. a and b APP-immunolabeled sections counterstained with Congo red for fibrillar amyloid deposits at 4 (a) and 6 (b) months of age showing the early occurrence of the neuritic pathology. The number of neuritic plaques progressively increases with age. APP-positive dystrophic neurites arise from glutamatergic neurons since the human APP transgene is exclusively expressed by principal neurons as shown in the inset. c A representative neuritic plaque formed by a core of congophilic fibrillar amyloid surrounded by numerous APP-positive dystrophic neurites. d Confocal image showing APP-positive dystrophic neurites (red) around a plaque stained with thioflavin-S (green). e Stereological quantification of the dystrophic neurites around plaques. The number of dystrophies/plaque increased with the size of plaque (μm²). Data are expressed as mean ± SD, *p < 0.05. Scale bars a and b 500 μm, inset 25 μm, c and d 10 μm. CA1–CA3 subfields of the hippocampus proper, DG dentate gyrus